Non-store cursor writing on a storage tube

ABSTRACT

This technique employs a split-screen storage tube wherein the top half of the viewing screen stores the video signal being viewed, and the bottom half, having a non-store characteristic, is used for the cursor. In order that the same deflection system can be used for both the viewed signal and the cursors, the writing of the viewed signal and the cursor is performed by time sharing the writing electron beam, there being no interference with the stored trace because of the small time spent in writing the cursor. The sweep voltage for the viewed signal is produced by a binary counter driven by a clock. The horizontal position of the cursor is presented in binary form. An astable multivibrator determines the frequency of writing the cursor and drives a monostable multivibrator that determines the duration of the cursor. The output signal of the monostable multivibrator and its complement control logic circuitry that couples the sweep voltage in binary form or the cursor horizontal position in binary form to a digital to analog convertor, the output of which drives the horizontal deflection system of the storage tube, resulting in time shared horizontal deflection of the electron beam in the store and non-store portions of the viewing screen. Also, the monostable multivibrator output signal and its complement controls circuitry which results in time shared vertical deflection of the electron beam in the store and non-store portions of the viewing screen. The cursor is vertically written by a sine wave oscillation starting from a predetermined vertical position in the non-stored portion of the viewing screen. In addition, the astable multivibrator output controls the writing electron gun to blank the electron beam during its deflections between the viewed signal and the cursor and vice-versa.

United States Patent Fielding NON-STORE CURSOR WRITING ON A STORAGE TUBE Primary Examiner-Reuben Epstein Att0mey-C. Cornell Remsen, Jr., Walter J. Baum, Paul W. H. Emminger, Charles L. Johnson, Jr., Philip M. Bolton, lsidore Togut, Edward Goldberg and Menotti J. Lombardi, Jr.

is] 3,670,200 [451 June 13, 1972 the top half of the viewing screen stores the video signal being viewed, and the bottom half, having a non-store characteristic, is used for the cursor. in order that the same deflection system can be used for both the viewed signal and the cursors, the writing of the viewed signal and the cursor is performed by time sharing the writing electron beam, there being no interference with the stored trace because of the small time spent in writing the cursor. The sweep voltage for the viewed signal is produced by a binary counter driven by a clock. The horizontal position of the cursor is presented in binary form. An astable multivibrator determines the frequency of writing the cursor and drives a monostable multivibrator that determines the duration of the cursor. The output signal of the monostable multivibrator and its complement control logic circuitry that couples the sweep voltage in binary form or the cursor horizontal position in binary form to a digital to analog convertor, the output of which drives the horizontal deflection system of the storage tube, resulting in time shared horizontal deflection of the electron beam in the store and non-store portions of the viewing screen. Also, the monostable multivibrator output signal and its complement controls circuitry which results in time shared vertical deflection of the electron beam in the store and non-store portions of the viewing screen. The cursor is vertically written by a sine wave oscillation starting from a predetermined vertical position in the non-stored portion of the viewing screen. In addition, the astable multivibrator output controls the writing electron gun to blank the electron beam during its deflections between the viewed signal and the cursor and vice-versa.

[ ABSTRACT This technique employs a split-screen storage tube wherein 8Claims, 1 Drawing Figure MONOSTAJLE Sol/RC6 o; CURSOk *Is flulrly wya HORIZONTA! POSITION IN GINARY FORM l A STABLE 26 1 Manly/mar O/gzlTAL 28 88a 5 ANALOG l9 2; com/ear: I 1 a? 8a MomsrAaLE 4 27 MuLr/WaRAr n INVERTER CURSOR 22 ii WRITE [3 03mm, C406. aM/ARY couvrse 55 2:

I arrow/rm E3 20 I I 1 L smnr ,4 CA r50 cave-4 weep sun I AMPLIF/E SHIFT 2x2 7 & 4 swesp 1 RESIST/Y5 wa nvPurj MATRIX AMPUF/ER l I MONOSTIABLE m" Mun/Wm 3 x-AXS AMPLIFIER MONOSIABLE mum/mum BACKGROUND OF THE INVENTION This invention relates to storage tubes and more particularly to the non-store cursor writing on a viewing screen having a store portion and a non-store portion.

In the past, non-store cursor writing on the surface of storage tubes has employed bombardment conductivity techniques. In this technique a separate and distinct electron gun and deflection system is employed for the non-store writing of the cursor, requiring gross changes in the storage tube voltages, and, hence, the requirement of compensation in the deflection systems. Due to this, registration between the cursor and the viewed video signal is difficult to achieve and costly. In addition, the stored image is affected by the cursor.

SUMMARY OF THE INVENTION An object of the present invention is to provide non-store cursor writing on the viewing screen of a split-screen storage tube that does not rely upon the bombardment conductivity technique.

Another object of the present invention is the provision of a non-store cursor writing technique that employs identical deflection sensitivity for the stored and non-stored traces through the use of the same deflection system, both horizontal and vertical, and constant electron gun voltage.

Still another object of the present invention is to provide a non-store cursor writing technique which employs an identical deflection system for all writing and the same tube operating conditions for both the store and non-store states, resulting in excellent registration between the cursor and viewed image.

A further object of the present invention is to provide a nonstore cursor writing technique wherein the stored image is completely unaffected by the writing of the cursor and the cursor can be moved with complete absence of smearing.

Still a further object of the present invention is to provide a non-store cursor writing technique wherein the writing of the viewed video signal and the cursor is performed by time sharing the electron beam of the storage tube.

A feature of the present invention is the provision of an arrangement to provide non-store cursor writing on a storage tube comprising the storage tube including an electron beam gun, horizontal electron beam deflection means disposed adjacent to the gun, vertical electron beam deflection means disposed adjacent to the gun, and a viewing screen having a horizontally disposed stored portion for storing a video signal, and a horizontally disposed non-store portion upon which the cursor is written, the non-store portion being vertically spaced from the store portion; a first source of video signal; a second source of first signal to control horizontal deflection of the electron beam in the store portion; a third source of second signal to control the horizontal deflection of the electron beam in the non-store portion; first means coupled to the second source, the third source and the horizontal deflection means to cause the electron beam to be deflected horizontally on a time shared basis by the first and second signals; second means coupled to the first means to produce a third signal to control the vertical deflection of the electron beam in the nonstore portion; and third means coupled to the second means, the first source, and the vertical deflection means to cause the electron beam to be deflected vertically on a time shared basis by the video signal and the third signal.

Another feature of the present invention is the provision of a fourth means in addition to the above-mentioned components coupled to the first means and the gun to blank the electron beam during the time the electron beam is moved between the stored video signal and the cursor and between the cursor and the stored video signal.

BRIEF DESCRIPTION OF THE DRAWING The above-mentioned and other features and objects of this invention and the manner of obtaining them will become more apparent by reference to the following description taken in conjunction with the drawing, the single FIGURE of which illustrates in block diagram form an embodiment in accordance with the principles of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The non-store cursor writing technique disclosed in the Figure employs a storage tube 1 including writing electron beam gun 2, vertical deflection system 3, horizontal deflection system 4, flood gun 5, and viewing screen 6, which is split into a store surface or portion 7 and a non-store surface or portion 8 with a vertical separation 9 present between surface 7 and surface 8. Details of the construction of storage tube 1 are well known in the art, one example of which is found in U. S. Pat. No. 3,214,631 and the co-pending application cited therein.

The technique of the present invention provides a nonstored cursor on viewing screen 6 in portion or surface 8 without the use of bombardment conductivity so that the identical deflection sensitivities are available for the stored image 10 and the non-stored cursor I! through the use of the same deflection sytstems 3 and 4 and constant voltages applied to electron beam gun 2.

In order that the same deflection system 3 and 4 can be used for both the viewed signal and the cursors (this causes nonlinearity to cancel) the writing is performed on viewing screen 6 by time-sharing the electron beam produced by gun 2 there being no resultant interference with the stored trace because of the small time spent in writing cursor 1 1.

As can be seen in the Figure, the horizontal or X axis deflec tion voltage is provided by amplifier 12 driven from digital to analog converter 13, the inputs of which are periodically, and for a small period of time, switched from sweep binary counter 14 to the binary number representing the desired cursor horizontal position provided by source 15.

While only one cursor 11 is shown, the system of the Figure can be extended to any number of cursors by having source 15 arranged with a plurality of registers each providing in binary form a different cursor horizontal position and an arrangement to cyclically scan these registers at a rate compatible with the system and with the desired cursor position so that a plurality of cursors 11 can be provided on the non-store surface 8 of viewing screen 6.

Counter 14 will be described herein as a down counter, but it should be noted that counter 14 can as well be an up counter. Counter 14 includes therein 11 stages each providing one bit of a binary number so that the value of n and the value of the frequency of the signal from clock 16 will determine the number of steps and the fineness of the steps of the sweep voltage applied to converter 13. The binary horizontal position of the cursor from source 15 will be provided by a binary number having the same number of bits, namely, n bits, as that of counter 14, thus this arrangement provides accurate registry between the cursor and the viewed image.

Counter 14 has all the stages therein set to a predetermined state with the start sweep" command signal. Counter 14 then counts down, the state of each stage being translated in converter 13 to a step sweep voltage until the state corresponding to the end of the sweep is recognized in circuit 17 which produces an output to terminate the counter counting. Circuit 17 could be an AND gate matrix to recognize a predetermined end count, such as 000000 for a down counter, or 1 l 111 l for an up counter.

Clock 16, as previously mentioned, determines the size of the steps. The frequency of the output signal of clock 16 and the number of stages of counter 14 are selected to provide a large number of steps so that the sweep as seen by an observer observing viewing screen 6 will appear purely linear.

The frequency at which the cursor is written is determined by the astable multivibrator l8 and the duration of the cursor is determined by monostable multivibrator 32.

In the absence of cursor commands, the electron beam is vertically positioned just above boundary 9 of viewing screen 6. Video input will cause the beam to deflect upwards further into the store surface 7. When cursor writing is required and the X or horizontal position of the cursor is provided by source 15,,the beam is deflected vertically downward to a fixed distance below the boundary 9 through the means of level shifter 20 which responds to the inverted output of multivibrator 32 as provided by inverter 21. The electron beam then moves up and down sinusoidally for the duration of the cursor write voltage to enscribe a vertical line. This is accomplished by the equipment including cursor write oscillator 22, the output of which is gated by gated amplifier 23, the gate pulse for amplifier 23 being provided by the output signal of multivibrator 32. The desired vertical level for the start of the cursor below boundary 9, as determined by shifter 20, and the gated oscillations at the output of amplifier 23 are combined with the video input in resistive matrix 24, the output of which is applied through the vertical or Y axis amplifier 25 to the vertical deflection system 3.

Level shifter circuit 20 is a circuit that will clamp the output of matrix 24 so that the vertical position for the start of cursor 11 below boundary 9 is at the same given level regardless of the video input supplied to matrix 24. Thus, cursor 11 will start on surface 8 at the same predetermined vertical position at all times and under all conditions of video signal amplitude.

Upon a cursor write command from multivibrator 18, the output from source 15 is coupled to AND gates 26-26n which are enabled by the output of multivibrator 32 which goes to a binary l condition when the cursor write command is received from the multivibrator 18 via multivibrator 19. Simultaneously, this binary l output will be inverted in invertor 21 and applied to AND gates 27-27n to render these AND gates inoperative and thereby stop the sweep of the electron beam on store sources 7 and enable the output from gate 26-26n to be applied through OR gates 28-28;: to converter 13 and thereby cause the electron beam to be deflected to the horizontal position of the cursor and simultaneously therewith cause the cursor to be written by the output of oscillator 22.

As illustrated on viewing screen 6, the image is interrupted at point A upon command from multivibrator 18 for a given period determined by multivibrator 32. The electron beam is then shifted and defected to the horizontal position B, the cursor is written and the electron beam returned to position C of image 10 to continue writing the image. At position D multivibrator 18 will emit another cursor write command which will cause the electron beam to be deflected again to position B, the cursor will be written and the electron beam is then deflected back to position E. The image 10 will then be continued to be written and when the electron beam reaches position F multivibrator 18 will provide another cursor write command which will cause the electron beam to be shifted to the horizontal position B where the cursor 11 is written and then the electron beam is deflected back to position G of image 10 to continue writing the image. Again at position H multivibrator 18 will provide another cursor write command which will cause the electron beam to be deflected to the horizontal position B, the cursor will be written and the electron beam will be returned to image 10 at position I. The illustration on the viewing screen 6 of the Figure shows the writing routine" as accomplished by the circuitry associated with storage tube 1. This clearly shows the mechanism by which the stored trace or image 10 is momentarily interrupted each time multivibrator 18 provides a cursor write command. The beam is moved to the cursor horizontal position, moved up and down by the output of amplifier 23 to make the cursor vertical line and then returned to the latest horizontal axis sweep position for image 10. It should be appreciated that the illustration in the Figure of this writing routine" shows a considerable gap in image 10 at the point of receipt of the cursor write command. This is done only for ease of explanation and actually the interruption in image 10 to permit cursor writing is very small and would not be perceptible to a person viewing viewing screen 6.

It will be appreciated that the deflection of the electron beam from the image 10 to cursor 11 at each command of multivibrator l8 and the return of the electron beam from cursor 11 to image 10 would provide appreciable unwanted electron beam images in this transition period. Therefore, some arrangement must be provided to gate the electron gun off during the transition periods from image 10 to cursor l1 and from cursor 11 to image 10. One such arrangement is illustrated in the Figure and includes monostable multivibrator 29 which responds to the leading edge of the output of multivibrator 19 to generate a delayed trigger for multivibrator 31 through inverter 30. By correctly arranging the timing of multivibrators 29 and 31, it can be arranged that the output of multivibrator 31 will exist during the transition from cursor 11 to image 10. Since the output of multivibrator 19 occurs immediately prior to the output of multivibrator 32, the output of multivibrator 19 can similarly be used to cover the transition from image 10 to cursor l1. Outputs from multivibrator 19 and 31 are OR ed in OR gate 33 and then applied to electron gun 2, where the necessary blanking during the transition takes place.

The advantages offered by the technique of the present invention when compared with the approaches or technique employed in the prior art as mentioned hereinabove under the heading Background of the Invention includes:

1. Since the identical deflection system and same tube operating conditions are used for both the store and nonstore state, excellent registration between the cursor and the stored image can be readily achieved; and

2. Since the store and non-store surfaces are optimized for their functions, the stored image is completely unaffected by the cursor and the cursor can be moved with complete absence of smearing.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is only made by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

I claim 1. An arrangement to provide non-store cursor writing on a storage tube comprising:

said storage tube including an electron beam gun, horizontal electron beam deflection means disposed adjacent said gun, vertical electron beam deflection means disposed adjacent said gun, and a viewing screen having a horizontally disposed store portion for storing a video signal and a horizontally disposed non-store portion upon which said cursor is written, said non-store portion being vertically spaced from said store portion;

a first source of video signal;

a second source of first signal to control horizontal deflection of said electron beam in said store portion;

a third source of second signal to control the horizontal deflection of said electron beam in said non-store portion;

first means coupled to said second source, said third source and said horizontal deflection means to cause said elec' tron beam to be deflected horizontally on a time shared basis by said first and second signals;

second means coupled to said first means to produce a third signal to control the vertical deflection of said electron beam in said non-store portion; and

third means coupled to said second means, said first source and said vertical deflection means to cause said electron beam to be deflected vertically on a time shared basis by said video signal and said third signal.

2. An arrangement according to claim 1, further including fourth means coupled to said first means and said gun to blank said electron beam during the time said electron beam is moved between said stored video signal and said cursor and between said cursor and said stored video signal.

3. An arrangement according to claim 1, wherein said second source includes a clock, a binary counter coupled to said clock, to provide said first signal said counter counting in a given direction from a predetermined starting count to a predeter- 5 mined ending count, a set signal coupled to said counter to set said counter in said predetermined starting count, and fourth means coupled to said counter to detect said predetermined ending count and produce a signal to stop the counting of said counter. 4. An arrangement according to claim 1 wherein said first and second signals are in binary form. 5. An arrangement according to claim 4, wherein said first means includes an astable multivibrator, a monostable multivibrator coupled to said astable multivibrator, an inverter coupled to said monostable multivibrator, a first set of AND gates coupled to said third source and said monostable multivibrator a second set of AND gates coupled to said second source and said inverter, a set of OR gates coupled to said first and second sets of 2 AND gates, and a digital-to-analog converter coupled to said set of OR gates. 6. An arrangement according to claim 1, wherein said second means includes 3 fourth means coupled to said first means responsive to the time of writing said cursor to provide a voltage at said third means to clamp said electron beam to a given vertical level on said non-store portion of said viewing screen, 3 a sine wave oscillator, and gate means coupled to said first means and said oscillator gated in response to the time of writing said cursor to pass said sine wave to said third means to cause the writing of said cursor on said non-store portion of said 4 viewing screen extending vertically from said given vertical level. 7. An arrangement according to claim 1, wherein said third means includes a resistive matrix coupled to said first means,

said first source and said vertical deflection means.

8. An arrangement according to claim 1, wherein said third source provides said second signal in binary form having n digits, where n is an integer greater than one; said second source includes a clock,

a binary counter coupled to said clock to provide said first signal in binary form having n digits, said counter counting in a given direction from a predetermined starting count to a predetermined ending count,

a set signal coupled to said counter to setsaid counter in said predetermined starting count, and

fourth means coupled to said counter to detect said predetermined ending count and produce a signal to stop the counting of said counter;

said first means includes an astable multivibrator a monostable multivibrator coupled to the output of said astable multivibrator,

an inverter coupled to the output of said monostable multivibrator,

a first set of n AND gates, one for each digit of said second signal, coupled to said third source and the output of said monostable multivibrator,

a second set of n AND gates, one for each stage of said counter, coupled to said counter and the output of said inverter,

a set of n OR gates each coupled to a corresponding different one of the AND gates of said first and second sets of AND agates, and a digital-to-an 0g converter coupled to the output of said set of OR gates; said second means includes fifth means coupled to the output of said inverter responsive to a binary 0" output signal therefrom to provide a voltage at said third means to clamp said electron beam to a given vertical level on said non-store portion of said viewing screen, a sine wave oscillator, and gate means coupled to the output of said monostable multivibrator and said oscillator in response to a binary 1 output signal from said monostable multivibrator to pass said sine wave to said third means to cause the writing of said cursor on said non-store portion of said viewing screen extending vertically from said given vertical level; and said third means includes a resistive matrix coupled to said first source, said fourth means, said gate means and said vertical deflection means. 

1. An arrangement to provide non-store cursor writing on a storage tube comprising: said storage tube including an electron beam gun, horizontal electron beam deflection means disposed adjacent said gun, vertical electron beam deflection means disposed adjacent said gun, and a viewing screen having a horizontally disposed store portion for storing a video signal and a horizontally disposed non-store portion upon which said cursor is written, said non-store portion being vertically spaced from said store portion; a first source of video signal; a second source of first signal to control horizontal deflection of said electron beam in said store portion; a third source of second signal to control the horizontal deflection of said electron beam in said non-store portion; first means coupled to said second source, said third source and said horizontal deflection means to cause said electron beam to be deflected horizontally on a time shared basis by said first and second signals; second means coupled to said first means to produce a third signal to control the vertical deflection of said electron beam in said non-store portion; and third means coupled to said second means, said first source and said vertical deflection means to cause said electron beam to be deflected vertically on a time shared basis by said video signal and said third signal.
 2. An arrangement according to claim 1, further including fourth means coupled to said first means and said gun to blank said electron beam during the time said electron beam is moved between said stored video signal and said cursor and between said cursor and said stored video signal.
 3. An arrangement according to claim 1, wherein said second source includes a clock, a binary counter coupled to said clock, to provide said first signal said counter counting in a given direction from a predetermined starting count to a predetermined ending count, a set signal coupled to said counter to set said counter in said predetermined starting count, and fourth means coupled to said counter to detect said predetermined ending count and produce a signal to stop the counting of said counter.
 4. An arrangement according to claim 1 wherein said first and second signals are in binary form.
 5. An arrangement according to claim 4, wherein said first means includes an astable multivibrator, a monostable multivibrator coupled to said astable multivibrator, an inverter coupled to said monostable multivibrator, a first set of AND gates coupled to said third source and said monostable multivibrator a second set of AND gates coupled to said second source and said inverter, a set of OR gaTes coupled to said first and second sets of AND gates, and a digital-to-analog converter coupled to said set of OR gates.
 6. An arrangement according to claim 1, wherein said second means includes fourth means coupled to said first means responsive to the time of writing said cursor to provide a voltage at said third means to clamp said electron beam to a given vertical level on said non-store portion of said viewing screen, a sine wave oscillator, and gate means coupled to said first means and said oscillator gated in response to the time of writing said cursor to pass said sine wave to said third means to cause the writing of said cursor on said non-store portion of said viewing screen extending vertically from said given vertical level.
 7. An arrangement according to claim 1, wherein said third means includes a resistive matrix coupled to said first means, said first source and said vertical deflection means.
 8. An arrangement according to claim 1, wherein said third source provides said second signal in binary form having n digits, where n is an integer greater than one; said second source includes a clock, a binary counter coupled to said clock to provide said first signal in binary form having n digits, said counter counting in a given direction from a predetermined starting count to a predetermined ending count, a set signal coupled to said counter to set said counter in said predetermined starting count, and fourth means coupled to said counter to detect said predetermined ending count and produce a signal to stop the counting of said counter; said first means includes an astable multivibrator a monostable multivibrator coupled to the output of said astable multivibrator, an inverter coupled to the output of said monostable multivibrator, a first set of n AND gates, one for each digit of said second signal, coupled to said third source and the output of said monostable multivibrator, a second set of n AND gates, one for each stage of said counter, coupled to said counter and the output of said inverter, a set of n OR gates each coupled to a corresponding different one of the AND gates of said first and second sets of AND gates, and a digital-to-analog converter coupled to the output of said set of OR gates; said second means includes fifth means coupled to the output of said inverter responsive to a binary ''''0'''' output signal therefrom to provide a voltage at said third means to clamp said electron beam to a given vertical level on said non-store portion of said viewing screen, a sine wave oscillator, and gate means coupled to the output of said monostable multivibrator and said oscillator in response to a binary ''''1'''' output signal from said monostable multivibrator to pass said sine wave to said third means to cause the writing of said cursor on said non-store portion of said viewing screen extending vertically from said given vertical level; and said third means includes a resistive matrix coupled to said first source, said fourth means, said gate means and said vertical deflection means. 